Coupling device for providing a communications link for RF broadband data signals to a power line and method for installing same

Abstract

A coupling device for providing a communications link for RF broadband data signals to a power line is disclosed. The coupling device comprises a high-pass filter element connected to the power line via a first port. The filter element allows RF broadband data signals to pass while low frequency signals are substantially attenuated. A second port connected to the high-pass filter element provides the RF broadband data signals to a RF broadband data signal line at a customer's premise. A drain coil connected to the high-pass filter element and connected to a ground provides grounding for low frequency signals but prevents the RF broadband data signals from being grounded. The second port and the drain coil are protected from power surges by a protective device connected in parallel to the drain coil. The coupling device is inexpensive to manufacture, essentially maintenance free, and easy to install. In a preferred embodiment such a coupling device is installable absent a step of disconnecting power to the power line which provides power to a customer's premise. Therefore, power supply to neighboring premises served by the same power line is not interrupted during installation.

What is claimed is:  
     
       1. A coupling device for providing a communications link for RF broadband data signals to a power line comprising: 
       a first port for connection to a power line;  
       a high-pass filter element connected to the first port, the filter element allowing RF broadband data signals to pass while substantially attenuating low frequency signals, wherein the high-pass filter element is connected to the first port via a cable having shielding spaced from the core at a sufficient distance to effectively limit noise resulting from the cable shielding in order to permit extraction of a RE broadband signal absent substantial noise; and,  
       a second port connected to the high-pass filter element for connection to a RF broadband data signal line.  
     
     
       2. A coupling device as defined in  claim 1  comprising an inductor connected to the high-pass filter element and connected to ground, the inductor providing grounding for low frequency signals but preventing the RE broadband data signals from being grounded. 
     
     
       3. A coupling device as defined in  claim 2  wherein the inductor has an inductance value such that a virtual ground for the coupling device is provided while substantial attenuation of the RE broadband data signals is avoided. 
     
     
       4. A coupling device as defined in  claim 2  comprising a spark gap connected in parallel to the inductor for protecting the second port and the inductor. 
     
     
       5. A coupling device as defined in  claim 4  wherein a self-resonant frequency of the high-pass filter element is high enough to ensure least possible data signal attenuation over the RF broadband data signal frequency range. 
     
     
       6. A coupling device as defined in  claim 5  wherein the high-pass filter element is partial-discharge free. 
     
     
       7. A coupling device as defined in  claim 6  comprising an impedance matching circuit to match the impedance of the coupling circuit with the impedance of the data signal line. 
     
     
       8. A coupling device as defined in  claim 7  wherein the impedance matching circuit comprises a transformer and a coupling capacitor. 
     
     
       9. A coupling device as defined in  claim 6  wherein the cable has a core and a concentric neutral shielding and wherein the neutral shielding is spaced from the core a sufficient distance to prevent substantial noise from occurring within the RF broadband signal. 
     
     
       10. A coupling device for providing a communications link for RF broadband data signals to a power line comprising: 
       a first port for connection to a power line;  
       a high-pass filter element connected to the first port, the filter element allowing RF broadband data signals to pass while substantially attenuating low frequency signals;  
       a second port connected to the high-pass filter element for connection to a RF broadband data signal line;  
       a drain coil connected to the high-pass filter element and connected to ground, the drain coil providing grounding for low frequency signals but preventing the RE broadband data signals from being grounded; and,  
       a protective device connected in parallel to the drain coil for protecting the second port and the drain coil.  
     
     
       11. A coupling device as defined in  claim 10  comprising a second protective device to enhance safety for the data signal line. 
     
     
       12. A coupling device for providing a communications link for RF broadband data signals to a power line comprising: 
       a first port for connection to a power line; a second port for connection to a power input line of a premise and electrically connected to the first port via a power passthrough for providing power to the premise, wherein the power passthrough comprises a cable having shielding spaced from the core at a sufficient distance to prevent substantial noise from occurring within the RF broadband data signal;  
       a high-pass filter element connected to the power passthrough, the filter element allowing RF broadband data signals to pass while substantially attenuating low frequency signals;  
       a third port connected to the high-pass filter element for connection to a RF broadband data signal line; a ground terminal for connection to ground;  
       a drain coil connected to the high-pass filter element and connected to the ground terminal, the drain coil providing grounding for low frequency signals but preventing the RF broadband data signals from being grounded; and,  
       a protective device connected in parallel to the drain coil for protecting the third port and the drain coil.  
     
     
       13. A coupling device as defined in  claim 12  wherein the first port, the second port and the power passthrough are integrated in a housing of the coupling device. 
     
     
       14. A coupling device as defined in  claim 12  wherein the first port, the second port and the power passthrough form a unit outside a housing of the coupling device and wherein the unit is connected to the coupling device via a flexible power cable. 
     
     
       15. A coupling device for providing a communications link for RF broadband data signals to a power line comprising: 
       a first port for connection to a power line;  
       a high-pass filter element connected to the first port, the filter element allowing RF broadband data signals to pass while substantially attenuating low frequency signals;  
       an inductor connected to the high-pass filter element and connected to ground, the inductor providing grounding for low frequency power signals but preventing the RF broadband data signals from being grounded; and,  
       a second port connected to the high-pass filter element for connection to a RF broadband data signal line.  
     
     
       16. A coupling device as defined in  claim 15  comprising a grounded housing. 
     
     
       17. A coupling device as defined in  claim 16  wherein the high-pass filter element comprises a coupling capacitor. 
     
     
       18. A method for installing a coupling device for providing a communications link for RF broadband data signals to a power line while the power line is provided with a power signal, the method comprising the steps of: 
       first connecting a ground terminal of the coupling device to a ground terminal connected to a ground and connecting a port of the coupling device for connection to a RF broadband data signal line to a same port of a RF broadband data signal network;  
       second connecting a port of the coupling device for connection to a power input line of a premise to a same port for feeding power to the premise; and,  
       third connecting a port of the coupling device for connection to a power line to the power line comprising a power signal.  
     
     
       19. A method as defined in  claim 18  wherein the ground terminal includes a housing of the coupling device.